1. Field of the Invention
The present invention relates to an ink jet recording system for recording by discharging ink droplets onto a recording medium. More particularly, the invention relates to a method for standardizing an ink jet recording head and an ink tank, using different discharging principles, to be made capable of maintaining compatibility between plural kinds of ink jet recording heads having different recording characteristics and operational characteristics, respectively, and a recording head, an ink jet recording method, and an information processing apparatus using such a standardizing method.
2. Related Background Art
A recording apparatus, which is used as output equipment for a printer, a copying machine, facsimile equipment, or a complex electronic equipment or work station including a computer, word processor, or the like, is structured to record images on a recording material (a recording medium), such as a paper sheet, thin plastic sheet, in accordance with image information. Depending on the method for forming images on a recording medium, recording apparatuses are classified into those using an ink jet method, a wire-dot method, a thermal method, and a laser beam method, among some others. Also, such classification is possible in accordance with scanning methods adopted for image recording.
For a serial type recording apparatus, which adopts a serial scanning method where main scanning is performed in a direction intersecting the conveying direction of a recording medium (sub-scanning direction), images are recorded (main scanned) by recording means mounted on a carriage that travels along the recording medium. After one line portion of recording is over, the recording sheet is carried by a given amount (pitch conveyance). After that, recording (main scanning) is resumed for images on the next line on the recording material whose feeding has come to a stop again. This operation is repeated to record on the entire recordable area of the recording material. On the other hand, for a line type recording apparatus, which records on a recording material by recording made only by sub-scanning in the conveying direction of the recording material, the recording material is set at a given recording position, and then, after one line portion is recorded altogether, a sheet feeding (pitch conveyance) operation is performed by a given amount. Further, images on the next line are recorded altogether. This operation is repeated to record on the entire recordable area of the recording material.
Of the recording apparatuses described above, the ink jet recording apparatus is to record by discharging ink from recording means (recording head) onto a recording material. The recording means is easily made compact to record highly precise images at high speeds. It is also possible for this apparatus to record on an ordinary paper sheet without any particular treatment given to it, which contributes to making its running costs lower. Also, with a non-impact method, its noises are lower. There is also an advantage, among others, that it is easy to record in colors using ink of different colors. Of these apparatuses, the line type ink jet apparatus, which is provided with many numbers of nozzles arranged in the sheet width direction, makes it possible to record at higher speeds. Particularly, among those having ink jet recording means, the apparatus that utilizes thermal energy for discharging ink makes it easy to manufacture a head provided with a highly densified arrangement of liquid flow paths (discharge port arrangement) by forming electrothermal transducing elements, electrodes, liquid flow paths, a ceiling plate, and others on an elemental substrate through the process of semiconductor manufacture, such as etching, deposition, spattering, and others. As a result, a head of this type can be made compact.
FIG. 1 is a perspective view which shows the structure of the conventional ink jet recording apparatus of this type. The ink jet recording apparatus comprises, broadly, a sheet feeding unit 20 that stacks paper sheets, sheet materials, or other recording media; a carriage unit 5 having a platen 39 for carrying and exhausting a recording medium, a feed roller, and an exhaust roller; a carriage unit that mounts a recording head 7 on it for recording; and a cleaning unit 6 for performing a recovery operation to clean the recording head 7 mounted on the carriage unit 5.
The cleaning unit 6 comprises a pump 60 for cleaning the recording head 7; a cap 61 for capping the recording head 7 in order to prevent the recording head 7 from drying out; and a driving change over arm 62 that switches the driving force from the carrier roller 36 to the sheet feeding unit 20 or to the pump 60. The driving change over arm 62 is arranged to fix a planet gear (not shown) that rotates centering on the shaft of the carrier roller 36 in a given position at a time other than sheet feeding or cleaning. Then, no driving force of the carrier roller 36 is transmitted to the sheet feeding unit 20 and the pump 60. When the carriage 50, which will be described later, travels, the driving change over arm 62 shifts in the direction indicated by an arrow A in FIG. 1. Then, the planet gear is freed. The planet gear shifts following the regular rotation or reverse rotation of the carrier roller 36. It is thus arranged that when the carrier roller rotates regularly, the driving force is transmitted to the sheet feeding unit 20. When the carrier roller rotates reversely, the driving force is transmitted to the pump 60. If no recording is performed or if the apparatus is left intact for a long time, the viscosity of ink in the discharge ports of the recording head 7 becomes high to cause defective discharging or some other unfavorable operations. Therefore, the discharge port surface of the recording head 7 is capped by the cap 61, and then, the interior of the cap 61 is sucked by means of the pump 60 to remove ink remaining in the discharge ports, the viscosity of which has become high, in order to recover the discharging performance of the recording head 7.
The carriage unit 5 is provided with a carriage 50 serving as means for attaching and detaching the recording head 7, which is arranged to be detachably mountable. The carriage 50 is slidably fitted over a guide shaft 81 and a guide rail 82 fixed to a chassis 8 in a direction at right angles to the carrying direction of the sheet material. Also, the carriage 50 is coupled to one position of a timing belt 83 tensioned around a pulley fixed to the output shaft of a carriage motor and an idle pulley 84 rotatively and axially supported. Then, the structure is arranged to enable the recording head 7 to reciprocate by the driving force of the carriage motor in the directions along the guide shaft 81.
Now, a description will be provided of the recording head 7 to be mounted on the carriage 50. FIGS. 2A, 2B, 2C and 2D are views which illustrate the recording head 7 formed integrally with an ink tank. Here, FIG. 2A is a view which shows the right side thereof. FIG. 2B shows the bottom thereof. FIG. 2C is the front view. FIG. 2D is a view which shows the left side thereof.
The recording head 7 is of a cartridge type, which is formed integrally with an ink tank 73 that retains ink to be supplied to the head unit 71, and which discharges ink downward in FIG. 2A. A sponge having ink impregnated in it is stuffed in the ink tank 73. The head unit 71 comprises an aluminum base plate 72, a silicon plate, a head substrate, a liquid chamber retaining ink temporarily, an ink filter, an ink supply tube 80 to supply ink from the ink tank 73 to the liquid chamber, and some others. The silicon plate and the head substrate are arranged on the base plate 72. For the silicon plate, a plurality of nozzles (discharge ports) 70 are arranged in a line in a density of 360 nozzles/inch. At the same time, heater elements, electrodes, and electric wires are formed on it to generate thermal energy for use of ink discharge. The arrangement direction of the discharge ports 70 is inclined at an angle of 1 to 4 degrees to a direction perpendicular to the main scanning direction of the recording head 7 for reasons derived from its driving. As a result, the head unit 71 is installed with an inclination with respect to the ink tank 73.
Here, the details of the structure of the head unit 71 will be described. FIG. 3 is a perspective view which shows the vicinity of the discharge ports 70 of the head unit 71. For the head unit 71, a plurality of discharge ports 70 are formed at given pitches on the discharge port surface 70a arranged to face the recording medium at a given gap. Along the wall surface of each of the liquid flow paths 70d, which is conductively connected with the common liquid chamber 70c and each of the discharge ports 70, each of the electrothermal transducing elements (heat generating resistor or the like) 70e is arranged to generate energy for use in ink discharge. The common liquid chamber 70c is conductively connected with the ink tank 73 (see FIGS. 2A to 2D). Here, the structure is arranged to supply ink from the ink tank 73 to the common liquid chamber 70c. Ink, which is supplied from the ink tank 73 and temporarily retained in the common liquid chamber 70c, is caused to flow in the liquid flow path 70d by means of capillary phenomenon, thus forming a meniscus at each discharge port 70b. The liquid flow path 70d is then conditioned to be filled with ink. At this juncture, when the electrothermal transducing element is energized to generate heat in accordance with recording signals, which are electric signals, ink on the electrothermal transducing element 70e is heated abruptly to generate film boiling for the creation of air bubbles in the liquid flow path 70d. By the expansion of the air bubbles, ink is discharged from the discharge port 70. Here, for the energy generating element that generates thermal energy, the electro-thermal transducing element is shown. However, such an element is not necessarily limited to it. A piezo-electric element may be used for exerting discharging pressure instantaneously by means of mechanical energy generated by this element. In this respect, electric signals, which are used for energizing each of the electrothermal transducing elements 70e, are provided by a printed-circuit board (not shown) that controls the operation of the recording apparatus through a flexible base board 56 (see FIG. 1) arranged for the carriage 50.
Now, the fundamental structure of the recording head has been described. However, in recent years, the structure generally adopted uses an ink tank that is made separable from a recording head in order to replace only the ink tanks, because there is more demand on the mixed use of the color recording and monochromatic recording or because the life of the recording head has been made longer. The present invention is designed to deal with such recording heads of the type that the ink tank is made separable, with the objectives being focused on the maintenance of compatibility between such heads. Hereinafter, a description will be provided of a recording head structured to be capable of exchanging ink tanks.
As shown in FIGS. 4A to 4C, the recording head 170 that can exchange ink tanks has the nozzle unit 171 for discharging ink, which is installed on the holder 173 together. FIG. 4A is a front view; FIG. 4B, a side view; and FIG. 4C, a bottom view, respectively. The holder 173 is a housing provided with an aperture on approximately 2/3 from the top of the front and on the upper surface. At the same time, the holder is partitioned into two portions by means of an inner plate 174. In each of the portions thus arranged, a black ink tank 175 for retaining black ink, and a color ink tank 176 for retaining three colors of ink of yellow, cyan, and magenta are detachably held, respectively. In this way, color recording is made possible, while saving space.
The attachment and detachment of the black ink tank 175 and the color ink tank 176 to and from the holder 173 are executed through the aperture of the holder 173 described above. Also, in the same manner as arranged for the recording head shown in FIGS. 2A to 2D, a stepped guide 74 is provided for the side of this holder, which is guided by the guide arm 513 (see FIG. 7A) when the holder is mounted on the head holder 51 (see FIGS. 6A and 6B). The holder is also provided with a contact surface 78, which serves as an electric contact means for making connection with the contact unit 561 (see FIG. 9) of the carriage 50 side, as well as a stopper 179. If the recording head is not placed in its regular position, the contact surface 78 and the contact unit 561 on the carriage 50 side are prevented from abutting upon other members.
The nozzle unit 171 is divided into the discharge port group 370B for use of black ink, the discharge port group 370Y for use of yellow ink, the discharge group 370C for use of cyan ink, and the discharge port group 370M for use of magenta ink corresponding to each color ink, respectively. Ink is supplied to each of the discharge port groups 370B, 370Y, 370C, and 370M through each of the ink supply tubes 306B, 306Y, 306C and 306M, which is dedicated to each of the groups, respectively. An ink lead out tube, which protrudes into the interior of the holder 173, is provided for each of the ink supply tubes 306B, 306Y, 306C, and 306M. Then, the structure is arranged to supply ink retained in each of the ink tanks 175 and 176 to the nozzle unit 171 through the respective ink lead out tubes and ink supply tubes 306B, 306Y, 306C and 306M when the black ink tank 175 and the color ink tank 176 are mounted on the holder 173.
Also, FIGS. 5A and 5B are views which show the method for installing each of the ink tanks 175 and 176 on the recording head 170. For each of the ink tanks 175 and 176, apertures 181 and 182 are arranged to supply ink to the recording head 170 side. Particularly, for the color ink tank 176, three apertures 182 are arranged with respect to each of the colors, yellow, magenta, and cyan. These apertures 181 and 182 are in contact with the leading end of the ink lead out tubes when the ink tanks 175 and 176 are installed on the holder 173. Then, ink flows into each of the ink lead out tubes.
The recording head 7 (FIGS. 2A to 2D) or the recording head 170 (FIGS. 4A to 4C) thus structured is installed on the carriage unit 5 of the ink jet recording apparatus, and driven in the main scanning direction. Now, in conjunction with FIGS. 6A, 6B, 7A, 7B, 8 and 9, a description will be provided of the carriage unit 5. The recording head 7 and the recording head 170 are provided with the installation unit structured in the same manner with respect to the carriage unit 5. The description given below is applicable to both the recording head 7 and the recording head 170 alike. In this respect, the description is provided of the recording head 170 of a type where the ink tank is separately arranged as the representative example hereof.
The attachment unit of the recording head 170 comprises the carriage 50, head holder 51, base cover 52, hook lever 53, contact spring 54, hook cover 55, flexible base board 56, and rubber pad 57 with respect to the carriage unit 5.
Here, FIG. 6A is a view which shows the process in which the head is mounted on the carriage. FIG. 6B is a view which shows the state after the head is mounted.
As shown in FIG. 6A and FIG. 6B, the recording head 170 is mounted on the head holder 51 along the guide 501 arranged for the carriage 50. The structure is then arranged to enable the holder to slide to the left-hand and right-hand sides. The head holder 51 is provided with the guide unit 511 for guiding the recording head 170; the contact surface 503 of the side plate 502 that stands vertically on the carriage 50; and the pressure unit 512 that presses the recording head 170 to the contact surface 503 and the positioning surface 504. There are three points on the positioning surface of the side plate 502 of the carriage 50. Then, the two points on the base plate 72 (see FIG. 2A), which are in the vicinity of the nozzle 70 (FIG. 3) of the recording head 170, and the one point, which is on the recording head 170 above the ink tank 73 (see FIGS. 2C and 2D), are arranged to face the positioning surface described above.
For the recording head 170, the contact surface 503 of the carriage 50 is arranged to be positioned inside the triangle formed by the three points of the positioning surface 504. The pressing position of the pressure unit 512 of the head holder 51 is also positioned within this triangle. Also, in the position that faces the pressure unit 512 of the head holder 51, the guide arm 513 is provided. When the recording head 170 should part from the contact surface 503, this guide arm 513 functions with respect to the recording head 170.
FIGS. 7A and 7B are views which illustrate the attachment mechanism of the head to be mounted on the carriage. Here, FIG. 7A is a view showing the upper surface thereof. FIG. 7B is a front view.
The hook lever 53 is rotatively installed on the side plate 502 of the carriage 50. For the rotational center of the hook lever 53, the contact spring 54 is provided to bias the hook lever 53. The hook cover 55 is installed to cover the hook lever 53 and hold the hook lever 53 not to fall off from the carriage 50. As shown in FIG. 7A and FIG. 7B, the hook lever 53 and the head holder 51 are provided with cams 516 and 531, which abut upon each other, respectively.
Here, the structure is arranged to enable the head holder 51 to shift in the left and right directions by the rotation of the hook lever 53. Also, by the biasing force of the contact spring 54, the head holder 51 presses the head through the hook lever 53.
On the side plate 502 of the carriage 50, the fitting pins 505a and 505b are arranged corresponding to the fitting holes 77a and 77b of the base plate 72 of the recording head 170, thus making it possible to perform accurate positioning. In this respect, FIG. 8 is a view which shows the carriage unit 5, observed from above.
On the contact surface 503 provided for the side plate 502 of the carriage 50, there is arranged the rubber pad 57 formed by an elastic material, such as silicon rubber having rubber hardness of 30 to 50 degrees, in order to establish electric contact with the recording head 170. Then, on the rubber pad 57, the contact unit 561 is arranged, which is prepared by forming the extrusion on the conductor of the flexible base board 56 by giving forming treatment to it. Then, the structure is arranged to deform the rubber pad 57 by a given amount when the recording head 170 is mounted, and the base plate 72 of the recording head 170 is in contact with the positioning surface 504 of the carriage 50 as described above. In this way, the electric contact is reliably implemented between the flexible base board 56 and the contact surface 78 of the recording head 170. Here, by this electric contact, the signal lines and power lines are coupled between the recording head 170 and the recording apparatus main body with each other. At the same time, the main body side recognizes the ID that distinctly indicates the kind of the recording head. Also, it is arranged for the main body side to read out the detected value of the temperature sensor arranged inside the recording head 170.
With the structure thus arranged, when images are formed on a sheet material, the carrier roller 36 and the pinch roller 37 carry the sheet material to the line position where images are formed. At the same time, the carriage 50 shifts to the line position of the image formation (the position in the direction perpendicular to the carrying direction of the sheet material) by means of the carriage motor, thus enabling such position of image formation to face the recording head 170. After that, in accordance with recording signals from the electric base board, the recording head 170 discharges ink from the head unit 71 onto the sheet material for the formation of images.
With the structure arranged as described above, the recording head 170 is detachably mounted and held on the carriage unit 5. Then, required positioning, electric contact and other related operations are performed. Then, depending on each of the printing modes, such as high quality (HQ) and high speed (HS), the recording head 170 is driven by the predetermined driving frequencies to perform each recording accordingly. Also, by exchanging recording heads to be mounted on the carriage unit 5, the execution of various kinds of recording becomes possible. For example, there are prepared a recording head for single color use (monochrome head) for recording in monochrome color, and a recording head for multiple color use, which is provided with nozzle lines and ink tanks retaining four color ink, such as black, cyan, magenta, and yellow. Then, when recording in monochrome color, the monochrome head is mounted, while for recording in colors, the head for multiple color use is mounted, hence making it possible to perform a desired recording. In this case, the ID (the kind) of the head to be used is detected to enable the recording apparatus main body to recognize the kind of head for switching over all the controlling operations corresponding to the head to be used. In this way, driving control, image processing, reliability control, and printing control are optimized, among some others. More specifically, the optimization is carried out with respect to the driving condition (the driving voltage, the driving pulses, the driving frequency, the pulse width control (PWM control) of the driving pulse, the driving method, and the like), the recovery condition and the recovery sequence (suction, pre-discharge, wiping, and the like), printing control (sheet feeding, mask, pass numbers, color processing, gamma correction, and the like), and the countermeasure taken for abnormal operation (control of abnormally high temperature), among some others.
There have been increasing demands for the wider utilization of bubble jet technologies and techniques for various products in many different fields, as discussed below.
For example, as to the demand on the improvement of discharging efficiency, the adjustment of the thickness of protection film has been studied to optimize the performance of heat generating elements. A study made of the effects on the enhancement of transfer efficiency of generated heat to liquids. Also, in order to obtain high quality images, there has been proposed a driving condition under which a liquid discharging method or the like is arranged to be able to execute good ink discharge at higher ink discharging speeds with better stabilized creation of air bubbles. Also, from the viewpoint of a high-speed recording, there has been proposed the improved configuration of liquid flow paths that makes it possible to obtain a liquid jet head capable of refilling liquid in the liquid flow paths at higher speeds in order to make up for the liquid that has been discharged.
Of the various configurations of liquid flow paths thus proposed, the structure of liquid flow paths is disclosed in the specification of Japanese Patent Laid-Open Application No. 63-199972 as shown in FIGS. 10A and 10B. The structure of the liquid flow paths and the method for manufacturing heads disclosed in the specification thereof are the inventions devised with attention given to the back waves (the pressure directed opposite to the direction toward the discharge ports, that is, pressure exerted in the direction toward the liquid chamber 12). The back waves produce an energy loss because such energy is not exerted in the discharging direction.
For the liquid flow path configuration shown in FIGS. 10A and 10B, heaters (heat generating elements) 2 are arranged on an elemental substrate. At the same time, a valve 90 is arranged away from the air bubble generating area formed by the heat generating element 2, and positioned on the side opposite to the discharge port 18 with respect to the heat generating element 2. As shown in FIG. 10B, this valve 90 is set at the initial position thereof such as adhesively bonded to the ceiling of the liquid flow path 10, and then, the valve is caused to hang down in the liquid flow path 10 along the creation of air bubble. It is also referred to in the disclosure that the invention is designed to control the aforesaid back waves partly by the provision of the valve 90 in order to suppress the energy loss. However, it is clearly understandable that the partial suppression of the back waves by means of the valve 90 is not practical for liquid discharge when studies are made precisely on the process in which the air bubbles are created in the liquid flow path 10 that retains the discharging liquid in it. In other words, the back waves themselves are not fundamentally related directly with discharging as described above. Of the pressures exerted by the air bubble, those directly related with discharging have already acted upon liquid so that the liquid is in the state of being discharged from the liquid flow path the moment the back waves are generated in the flow path as shown in FIG. 10A. Therefore, even if the back waves are suppressed, it is clear that no significant influence is exerted on the liquid discharge, not to mention the partial suppression of the back waves.
Also, in accordance with the conventional ink jet recording method described above, each of the heat generating elements repeats heating, while being in contact with ink. As a result, deposit is accumulated on the surface of each heat generating element due to burning of ink. Depending on the kinds of ink, such deposit is made in a considerable quantity, and results in the unstabilized creation of air bubbles, hence making it difficult to perform ink discharge in good condition. Also, it is desired to provide a method for performing discharge in good condition without changing the quality of discharging liquid even when the liquid used has the nature such as to easily deteriorate by the heat application or the liquid has the nature such as to make sufficient foaming difficult. Here, with this in view, there has been proposed a method for discharging liquid by transferring pressure exerted by foaming to discharging liquid, while arranging means for separating the liquid used to create air bubbles by the application of heat (foaming liquid) and the liquid for use of discharges (discharging liquid) as different liquids, such as disclosed in the specifications of Japanese Patent Laid-Open Application No. 61-69467, Japanese Patent Laid-Open Application No. 55-81172, U.S. Pat. No. 4,480,259, among some others. In accordance with these disclosures, the structure is arranged to completely separate ink serving as discharging liquid, and foaming liquid by use of silicon rubber or some other flexible film so as not to allow the discharging liquid to be directly in contact with the heat generating elements, and at the same time, to transfer pressure exerted by foaming of the foaming liquid to the discharging liquid by means of the deformation of the flexible film. With a structure of the kind, it is attained to prevent the deposit from being accumulated on the surface of each heat generating element, to provide the improved degree of selection freedom of discharging liquids, or the like.
However, the structure that completely separates discharging liquid and foaming liquid as described above is the one whereby to transfer pressure, exerted at the time of foaming to discharging liquid by means of the deformation of the flexible film, brought about by its expansion and contraction. Therefore, the pressure exerted by the deforming thereof is absorbed by the flexible film to a considerable extent. Also, the amount of deformation of the flexible film is not large. As a result, although it is possible to obtain the effect that discharging liquid and foaming liquid are made separable, there is a fear that discharging efficiency and discharging power are lowered after all.
As described above, further enhancement of discharging characteristics is desired for the method for discharging liquid by forming air bubbles (particularly, air bubbles created following film boiling) in each of the liquid flow paths. Under the circumstances, therefore, the inventor et al. hereof have reverted to making studies on the principle of the discharge of droplets, and have made the technical analyses given below in order to provide a novel type droplet discharging method utilizing air bubbles, as well as heads and others to be used for such novel type method. The first technical analysis is to begin with the operation of the movable member in each of the liquid flow paths, such as an analysis on the principle of the mechanism of such movable member in the liquid flow path. The second analysis is to begin with the principle of droplet discharging by means of air bubbles, and the third analysis is to begin with the bubble generation area of each heat generating element for use of air bubble creation. As a result, while shedding light upon the aspects that have not been taken into consideration for the conventional art, it is made possible to improve the fundamental discharging characteristics of the liquid discharging method for creating each of the air bubbles (particularly, the air bubble following film boiling) in each of the liquid flow paths to such a high level that cannot be anticipated in accordance with the conventional art.
In other words, the inventor et al. hereof have established a completely new technique to control air bubbles positively by arranging the positional relationship between the fulcrum of a movable member and the free end thereof in such a manner as to locate the free end on the discharge port side, that is, on the downstream side or by arranging the movable member to face each heat generating element or air bubble generating area. The present invention based upon the new technique. More specifically, in terms of energy to be given to a discharging amount by an air bubble itself, the developing component of the air bubble on the downstream side should be taken into consideration as the greatest element for the remarkable enhancement of the discharging characteristics. In other words, it has been found that the developing component of the air bubble on the downstream side should be converted efficiently so as to be directed toward discharging in order to enhance the discharging efficiency and the discharging speed as well. With this in view, it has been arranged to positively shift the developing component of the air bubble on the downstream side to the free end side of the movable member, thus having completed the invention of an extremely high technical standard as compared to the conventional liquid discharging method.
For this invention, it is found preferable to take the heat generating area for the creation of each of the air bubbles into consideration, which is the downstream side of the center line passing each of the center areas of electrothermal transducing elements in the flowing direction of liquid, for example, or take the structural elements, such as each movable member and liquid flow path into consideration, which are related to the development of each air bubble on the downstream side of the area center for its creation.
In addition to the techniques described above, the inventor et al. hereof have devised the structure of the liquid flow paths and the configuration of the heat generating elements to suppress the back waves and the developing component of each air bubble that advances in the direction opposite to the liquid supply direction, while effectuating the further enhancement of discharging power, thus leading to the introduction of an epoch-making technique that makes it possible to direct the flow of the discharging liquid in one way.
Now, the ink jet recording head produced in accordance with such new discharging principle requires driving condition (such as voltage, driving frequency) fit for the values of physical properties of discharging liquid (ink), such as viscosity, and resolution, which are different from those of the conventional ink jet recording head referred to in the description of the related background art. Therefore, the ink jet recording head that adopts the new discharging principle (hereinafter referred to as a novel type ink jet recording head) needs to be mounted on a novel type ink jet recording apparatus, as well as to be supplied with ink that fits the use of the novel type ink jet recording head. When these needs are satisfied, the novel type ink jet recording head demonstrates its characteristic performance to the maximum. In the description given below, only the so-called ink tank separation type ink jet recording head is taken into account. This ink jet recording head uses the ink tank, which is made separable from the head unit thereof, and it is arranged to exchange ink tanks alone.
For the novel type ink jet recording head, it should be considered that this head is mounted on the novel type recording apparatus in order to discharge novel type ink that fits the novel type ink jet recording head appropriately. (Likewise, for the conventional recording head, it should be ideal to mount the conventional head on the conventional recording apparatus for discharging conventional ink). Desirably, however, the arrangement should be made so that an ink tank retaining the conventional ink is installed on the novel type ink jet recording head, and then, mounted on the novel type ink jet recording apparatus in an emergency, such as ink shortage or it is made possible to use novel type ink for the conventional recording head or recording apparatus to cope with such emergency. In other words, it is desirable to maintain compatibility between the novel type ink and recording head or novel type recording apparatus, and the conventional ink and recording head or conventional recording apparatus. In this case, it is preferable to maintain compatibility between the novel and conventional printer drivers for driving a recording apparatus in accordance with image data.
However, it is impossible to enhance the compatibility between these two kinds if only the configurations of the coupling units of carriage are made equal for recording apparatuses, among the configurations of recording heads, or the configurations of the coupling units between ink tank and recording head are made equal between the novel and conventional ones. It is also impossible to attain the optimization of image qualities, recording speeds, operational reliability, and other related requirements within the allowable combination of ink, recording heads, and recording apparatuses. Also, no proposal has been made as to any method for preventing damage from being caused to the recording apparatus main body or the recording head for reasons such as the supply of inappropriate ink being conducted. If ink should be switched over while the recording head is in use, there is a possibility that the mixture of different kinds of ink brings about impediments. In order to attain good recording by enhancing the compatibility between ink, recording heads, and recording apparatuses, there are obstacles yet to be removed as given below.
(1) Ink for High Speed Recording
As a novel type ink, the refilling characteristic and fixation capability of ink should be improved to make such ink usable for a high speed recording. In other words, ink, which is made usable for discharging at higher driving frequencies, is adopted. In this case, if such novel type ink is used for the conventional recording head or recording apparatus, a discrepancy takes place between the characteristic of ink and the estimated characteristic of the conventional head or the estimated image processing, head control, carriage control and other related control of the conventional recording apparatus main body. In this respect, the refilling characteristic and fixation capability of the ink thus prepared for a high speed recording are enhanced by improving the permeability, viscosity, and surface tension of ink, among some others.
(2) Ink Usable for an Ordinary Paper Sheet
Ink is improved so that no bleeding or feathering may be brought about as novel type ink is used for printing on an ordinary paper sheet. Even in this case, a discrepancy takes place with respect to the image processing, head control, and operational reliability control if such improved ink is used for the conventional recording head or recording apparatus. Here, bleeding, feathering, coloring, density, fixation, or other properties of ink usable for an ordinary paper sheet are enhanced to be usable as a novel type ink by improving its permeability, viscosity, reactivity (to heat and light), polarity, among some other properties.
(3) Ink of Higher Reliability
The evenness, fixation, evaporation, and other properties of the novel type ink are improved to provide an enhanced reliability. If such improved ink is used for the conventional recording head or recording apparatus, a discrepancy takes place with respect to the head control and operational reliability control, among some others.
(4) Ink for a Higher Image Quality
The coloring, density and other properties of the novel type ink ink are enhanced to make it usable for recording images in higher quality. If such improved ink is used for the conventional recording head or recording apparatus, a discrepancy takes place with respect to image processing, head control, and operational reliability control, among some others. In this respect, the permeability, viscosity, reactivity (to heat and light), and polarity are enhanced, among some other properties, to obtain improved characteristics of bleeding, feathering, coloring, density, fixation, and the like.
(5) Compatibility Between the Contact Units of Recording Heads
The layout of contacts, the number of contact pads, and other related elements are yet to be discussed for the utilization of a higher performance of the novel type recording head, while being provided with the common terminals usable for the conventional recording head.
(6) Compatibility Between Driving Conditions
As compared with the conventional recording head, the driving frequency and resolution are enhanced for the novel type recording head. However, a discrepancy takes place between the novel type recording head and the conventional one with respect to head control if a high speed recording and high quality image recording are attempted, while fully utilizing such enhanced driving frequency and resolution.
(7) Compatibility Between Recovery Conditions, and Recovery Sequences (recovery by means of suction, pre-discharge, and wiping of discharge port surface), Among Some Others.
Since the structure of the liquid flow paths and ink to be used are different, the sucking condition and others are made different, and thus a discrepancy takes place with respect to the recovery sciences of the novel type recording head and the conventional one in some cases. Also, as described later, the novel type recording head is arranged by a single liquid flow path structure or by a two-flow path structure. In some cases, the sucking condition may be different even between these structures of the novel type recording head alone. (8) Compatibility between printing controls (sheet feeding, masking, number of passes, color processing, .gamma. correction, and the other factors) The modification of ink properties, and resolution may result in discrepancies between change of states with respect to the recorded images (colors, .gamma. values, dot diameters, and textures). (9) Compatibility between countermeasures against abnormal operations (control of abnormally high temperature, ink dropping from discharge ports, detection of disabled discharges, and the like) Since the structures of recording heads are different, the specific heat, heat capacitance, heat radiation, and sensor characteristics are caused to change. As a result, a discrepancy takes place between the countermeasures that should be taken by the novel and conventional recording heads or recording apparatuses.
The novel type ink jet recording head produced in accordance with the new discharging principle has a two-flow path structure in its inner arrangement of the head. Liquid supplied by means of the movable member described above to the portion on the air bubble generating area side is mainly used for the creation of air bubbles for discharging. For the novel type ink jet recording head thus structured, it is possible to arrange the supply of discharging liquid used mainly for discharging, and the supply of foaming liquid, used for the creation of air bubbles for discharging separately. These foaming liquid and discharging liquid may be made of one and the same liquid or different ones. Therefore, depending on the cases where discharging liquid and foaming liquid are separated by means of the inner structure of the recording head and where these liquids are not separated, the driving condition (such as the driving frequency, the width of driving pulse, and the resolution) and the abnormal operation countermeasures (such as the control of abnormally high temperature, ink dropping from the discharge ports, detection of disabled discharges, and the like) may present discrepancies with regard to the compatibility aspect even for the novel type recording head itself in some cases.
When foaming liquid and discharging liquid are made different, the operational characteristics may differ depending on the kinds of such liquids, whether or not these liquid are mutually mixable. Then, conceivably, discrepancies may take place with respect to compatibility between novel type recording heads themselves as to the aspects of driving conditions referred to in paragraph (6) above and countermeasures taken with respect to abnormal operation referred to in paragraph (9) above. Particularly, when reactive components may be contained in foaming liquid and discharging liquid, respectively, for the enhancement of coloring and fixation of ink on a recording medium, it is necessary to give fullest attention to the compatibility with respect to the printing control (such as sheet feeding, masking, number of passes, color processing, .gamma. correction, and the like) referred to in paragraph (8) above. It becomes possible to use highly viscous liquid as discharging liquid if foaming liquid and discharging liquid are separated. The fullest attention should be given to the compatibility of the recovery conditions and recovery sciences (such as suction/compression recovery, pre-discharges, wiping of the discharge port surface) as referred to in paragraph (7) above.
As described above, there are many problems yet to be solved as to the compatibility between the novel type ink and the conventional recording head or recording apparatus or between the conventional type recording head and the novel type ink, and further, between various novel types of ink and recording head, and then, to make it possible to perform the best recording on the assumption of the combination of ink, recording heads, and recording apparatuses thus given.